Messages in this thread Patch in this message | | | From | Ian Rogers <> | Date | Mon, 24 Jan 2022 18:09:50 -0800 | Subject | Re: [PATCH] perf map: Fix namespace memory leak |
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Hi,
As with: https://lore.kernel.org/linux-perf-users/20220122045811.3402706-4-irogers@google.com/ I implemented REFCNT_CHECKING for nsinfo (I'll mail it soon). This more accurately identifies the problem. In one run I got: ``` ================================================================= ==3900722==ERROR: AddressSanitizer: attempting double-free on 0x602000026710 in thread T6: #0 0x7f9a1dd6f4d7 in __interceptor_free ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:127 #1 0x5650d04cb29c in nsinfo__put util/namespaces.c:259 #2 0x5650d04aba93 in map__new util/map.c:198 #3 0x5650d04a11f6 in machine__process_mmap2_event util/machine.c:1798 #4 0x5650d04a24bf in machine__process_event util/machine.c:2019 #5 0x5650d03e78b3 in perf_event__process util/event.c:567 #6 0x5650d056e3bb in perf_tool__process_synth_event util/synthetic-events.c:65 #7 0x5650d05711a6 in perf_event__synthesize_mmap_events util/synthetic-events.c:501 #8 0x5650d0572fc0 in __event__synthesize_thread util/synthetic-events.c:792 #9 0x5650d05739fd in __perf_event__synthesize_threads util/synthetic-events.c:929 #10 0x5650d0573cbd in synthesize_threads_worker util/synthetic-events.c:961 #11 0x7f9a1dc48d7f in start_thread nptl/pthread_create.c:481 #12 0x7f9a1cfdcb6e in clone (/lib/x86_64-linux-gnu/libc.so.6+0xfcb6e)
0x602000026710 is located 0 bytes inside of 8-byte region [0x602000026710,0x602000026718) freed by thread T13 here: #0 0x7f9a1dd6f4d7 in __interceptor_free ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:127 #1 0x5650d04cb29c in nsinfo__put util/namespaces.c:259 #2 0x5650d04aba93 in map__new util/map.c:198 #3 0x5650d04a11f6 in machine__process_mmap2_event util/machine.c:1798 #4 0x5650d04a24bf in machine__process_event util/machine.c:2019 #5 0x5650d03e78b3 in perf_event__process util/event.c:567 #6 0x5650d056e3bb in perf_tool__process_synth_event util/synthetic-events.c:65 #7 0x5650d05711a6 in perf_event__synthesize_mmap_events util/synthetic-events.c:501 #8 0x5650d0572fc0 in __event__synthesize_thread util/synthetic-events.c:792 #9 0x5650d05739fd in __perf_event__synthesize_threads util/synthetic-events.c:929 #10 0x5650d0573cbd in synthesize_threads_worker util/synthetic-events.c:961 #11 0x7f9a1dc48d7f in start_thread nptl/pthread_create.c:481
previously allocated by thread T3 here: #0 0x7f9a1dd6f7cf in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145 #1 0x5650d04cb17f in nsinfo__get util/namespaces.c:244 #2 0x5650d04ab7df in map__new util/map.c:150 #3 0x5650d04a11f6 in machine__process_mmap2_event util/machine.c:1798 #4 0x5650d04a24bf in machine__process_event util/machine.c:2019 #5 0x5650d03e78b3 in perf_event__process util/event.c:567 #6 0x5650d056e3bb in perf_tool__process_synth_event util/synthetic-events.c:65 #7 0x5650d05711a6 in perf_event__synthesize_mmap_events util/synthetic-events.c:501 #8 0x5650d0572fc0 in __event__synthesize_thread util/synthetic-events.c:792 #9 0x5650d05739fd in __perf_event__synthesize_threads util/synthetic-events.c:929 #10 0x5650d0573cbd in synthesize_threads_worker util/synthetic-events.c:961 #11 0x7f9a1dc48d7f in start_thread nptl/pthread_create.c:481
Thread T6 created by T0 here: #0 0x7f9a1dd17716 in __interceptor_pthread_create ../../../../src/libsanitizer/asan/asan_interceptors.cpp:216 #1 0x5650d05745eb in perf_event__synthesize_threads util/synthetic-events.c:1039 #2 0x5650d05789fc in __machine__synthesize_threads util/synthetic-events.c:1791 #3 0x5650d0578a81 in machine__synthesize_threads util/synthetic-events.c:1802 #4 0x5650d024edd8 in __cmd_top /usr/local/google/home/irogers/kernel-trees/kernel.org/tip/tools/perf/builtin-top.c:1273 #5 0x5650d025629b in cmd_top /usr/local/google/home/irogers/kernel-trees/kernel.org/tip/tools/perf/builtin-top.c:1774 #6 0x5650d03b132b in run_builtin /usr/local/google/home/irogers/kernel-trees/kernel.org/tip/tools/perf/perf.c:313 #7 0x5650d03b188d in handle_internal_command /usr/local/google/home/irogers/kernel-trees/kernel.org/tip/tools/perf/perf.c:365 #8 0x5650d03b1c52 in run_argv /usr/local/google/home/irogers/kernel-trees/kernel.org/tip/tools/perf/perf.c:409 #9 0x5650d03b246b in main /usr/local/google/home/irogers/kernel-trees/kernel.org/tip/tools/perf/perf.c:539 #10 0x7f9a1cf077ec in __libc_start_main ../csu/libc-start.c:332
Thread T13 created by T0 here: #0 0x7f9a1dd17716 in __interceptor_pthread_create ../../../../src/libsanitizer/asan/asan_interceptors.cpp:216 #1 0x5650d05745eb in perf_event__synthesize_threads util/synthetic-events.c:1039 #2 0x5650d05789fc in __machine__synthesize_threads util/synthetic-events.c:1791 ``` That is thread 3 had created the wrapper object around the nsinfo, thread 13 had put and freed it which cause a double free when thread 6 tried to do the same thing. How did thread 6 and 13 have the same value for dso->nsinfo? In this patch we read then put the value, as the put is slow another thread reads and puts the value too. We need to atomically swap the value of dso->nsinfo with nsi and then do a put on nsi which holds the old value of dso->nsinfo. The question is how to do the swap?
C11 has atomic_exchange, but Makefile.config sets the std as gnu99. C11 is used in some selftests. atomic_t and atomic_long_t aren't guaranteed to be 64-bit, a long can be 32-bit with 64-bit pointers. Using a non-atomic swap fixes the issue, memory leak, etc. but clearly this needs to be atomic. My preference would be to bump to C11, but I can do a linux atomic or poor man's swap if others prefer. Wdyt?
Thanks, Ian
On Tue, Nov 30, 2021 at 9:20 AM Ian Rogers <irogers@google.com> wrote: > > On Tue, Nov 30, 2021 at 7:00 AM Arnaldo Carvalho de Melo > <acme@kernel.org> wrote: > > > > Em Sun, Nov 28, 2021 at 04:40:26PM +0100, Jiri Olsa escreveu: > > > On Thu, Nov 18, 2021 at 11:37:14AM -0800, Ian Rogers wrote: > > > > This leak was happening reliably with test "Lookup mmap thread" with > > > > stack traces like: > > > > > > > > Direct leak of 5504 byte(s) in 172 object(s) allocated from: > > > > #0 0x7f4685e47987 in __interceptor_calloc > > > > #1 0x56063b974c2a in nsinfo__new util/namespaces.c:142 > > > > #2 0x56063b9781ff in thread__new util/thread.c:70 > > > > #3 0x56063b944953 in ____machine__findnew_thread util/machine.c:543 > > > > #4 0x56063b944ac6 in __machine__findnew_thread util/machine.c:574 > > > > #5 0x56063b944b36 in machine__findnew_thread util/machine.c:584 > > > > #6 0x56063b94c892 in machine__process_fork_event util/machine.c:1954 > > > > #7 0x56063b94cc1f in machine__process_event util/machine.c:2019 > > > > #8 0x56063b894f18 in perf_event__process util/event.c:567 > > > > #9 0x56063ba17951 in perf_tool__process_synth_event util/synthetic-events.c:65 > > > > #10 0x56063ba19086 in perf_event__synthesize_fork util/synthetic-events.c:287 > > > > #11 0x56063ba1c39d in __event__synthesize_thread util/synthetic-events.c:775 > > > > #12 0x56063ba1cf6f in __perf_event__synthesize_threads util/synthetic-events.c:929 > > > > #13 0x56063ba1d4ab in perf_event__synthesize_threads util/synthetic-events.c:1000 > > > > #14 0x56063b821a3d in synth_all tests/mmap-thread-lookup.c:136 > > > > #15 0x56063b821c86 in mmap_events tests/mmap-thread-lookup.c:174 > > > > #16 0x56063b8221b7 in test__mmap_thread_lookup tests/mmap-thread-lookup.c:230 > > > > > > > > The dso->nsinfo is overwritten, but without a nsinfo__put this can leak > > > > the overwritten nsinfo. > > > > > > > > Signed-off-by: Ian Rogers <irogers@google.com> > > > > > > nice catch! > > > > > > Acked-by: Jiri Olsa <jolsa@redhat.com> > > > > This one is tricky, I have to retrieve the details from last time this > > surfaced, but try: > > > > # perf top -F 10000 > > > > leave it for a while and press 'q': > > > > perf: /home/acme/git/perf/tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. > > Aborted (core dumped) > > > > I reproduced the above assertion a few times, now I'm not being able, > > probably some namespace related activity took place when it hit. > > I was able to reproduce in about 1 run in 3. With address sanitizer > the core dump turns into a heap-use-after-free with a report of: > > ==235440==ERROR: AddressSanitizer: heap-use-after-free on address > 0x6030000485c8 at pc 0x55d8b882bfb7 bp 0x7fffd3426e90 sp > 0x7fffd3426e88 > READ of size 4 at 0x6030000485c8 thread T0 > #0 0x55d8b882bfb6 in __read_once_size ./tools/include/linux/compiler.h:132 > #1 0x55d8b882bfb6 in atomic_read > ./tools/include/asm/../../arch/x86/include/asm/atomic.h:28 > #2 0x55d8b882c35c in refcount_sub_and_test > ./tools/include/linux/refcount.h:123 > #3 0x55d8b882c45e in refcount_dec_and_test > ./tools/include/linux/refcount.h:148 > #4 0x55d8b882d4af in nsinfo__put util/namespaces.c:204 > #5 0x55d8b87adecd in __nsinfo__zput util/namespaces.h:65 > #6 0x55d8b87b4bcc in dso__delete util/dso.c:1327 > #7 0x55d8b87b4c8d in dso__put util/dso.c:1342 > #8 0x55d8b87fb23b in dsos__purge util/machine.c:182 > #9 0x55d8b87fb2e3 in dsos__exit util/machine.c:190 > #10 0x55d8b87fb46e in machine__exit util/machine.c:222 > #11 0x55d8b87fb715 in machines__exit util/machine.c:262 > #12 0x55d8b88149d2 in perf_session__delete util/session.c:305 > #13 0x55d8b85c0924 in cmd_top ./tools/perf/builtin-top.c:1781 > #14 0x55d8b87176b7 in run_builtin ./tools/perf/perf.c:313 > #15 0x55d8b8717c10 in handle_internal_command ./tools/perf/perf.c:365 > #16 0x55d8b8717fcd in run_argv ./tools/perf/perf.c:409 > #17 0x55d8b87187bc in main ./tools/perf/perf.c:539 > > 0x6030000485c8 is located 24 bytes inside of 32-byte region > [0x6030000485b0,0x6030000485d0) > freed by thread T0 here: > #0 0x7fb6e7c454d7 in __interceptor_free > ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:127 > #1 0x55d8b882d41a in nsinfo__delete util/namespaces.c:192 > #2 0x55d8b882d4bf in nsinfo__put util/namespaces.c:205 > #3 0x55d8b87adecd in __nsinfo__zput util/namespaces.h:65 > #4 0x55d8b87b4bcc in dso__delete util/dso.c:1327 > #5 0x55d8b87b4c8d in dso__put util/dso.c:1342 > #6 0x55d8b87fb23b in dsos__purge util/machine.c:182 > #7 0x55d8b87fb2e3 in dsos__exit util/machine.c:190 > #8 0x55d8b87fb46e in machine__exit util/machine.c:222 > #9 0x55d8b87fb715 in machines__exit util/machine.c:262 > #10 0x55d8b88149d2 in perf_session__delete util/session.c:305 > #11 0x55d8b85c0924 in cmd_top ./tools/perf/builtin-top.c:1781 > #12 0x55d8b87176b7 in run_builtin ./tools/perf/perf.c:313 > #13 0x55d8b8717c10 in handle_internal_command ./tools/perf/perf.c:365 > #14 0x55d8b8717fcd in run_argv ./tools/perf/perf.c:409 > #15 0x55d8b87187bc in main ./tools/perf/perf.c:539 > > previously allocated by thread T11 here: > #0 0x7fb6e7c45987 in __interceptor_calloc > ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154 > #1 0x55d8b882ceaa in nsinfo__new util/namespaces.c:142 > #2 0x55d8b883047f in thread__new util/thread.c:70 > #3 0x55d8b87fcb93 in ____machine__findnew_thread util/machine.c:543 > #4 0x55d8b87fcd06 in __machine__findnew_thread util/machine.c:574 > #5 0x55d8b87fcd76 in machine__findnew_thread util/machine.c:584 > #6 0x55d8b8804ad2 in machine__process_fork_event util/machine.c:1954 > #7 0x55d8b8804e5f in machine__process_event util/machine.c:2019 > #8 0x55d8b874cf18 in perf_event__process util/event.c:567 > #9 0x55d8b88cfbd1 in perf_tool__process_synth_event > util/synthetic-events.c:65 > #10 0x55d8b88d1306 in perf_event__synthesize_fork > util/synthetic-events.c:287 > #11 0x55d8b88d461d in __event__synthesize_thread util/synthetic-events.c:775 > #12 0x55d8b88d51ef in __perf_event__synthesize_threads > util/synthetic-events.c:929 > #13 0x55d8b88d54af in synthesize_threads_worker util/synthetic-events.c:961 > #14 0x7fb6e7b1eead in start_thread nptl/pthread_create.c:463 > > Thread T11 created by T0 here: > #0 0x7fb6e7bed716 in __interceptor_pthread_create > ../../../../src/libsanitizer/asan/asan_interceptors.cpp:216 > #1 0x55d8b88d5ddd in perf_event__synthesize_threads > util/synthetic-events.c:1039 > #2 0x55d8b88da3b8 in __machine__synthesize_threads > util/synthetic-events.c:1791 > #3 0x55d8b88da43d in machine__synthesize_threads > util/synthetic-events.c:1802 > #4 0x55d8b85b9378 in __cmd_top ./tools/perf/builtin-top.c:1273 > #5 0x55d8b85c0811 in cmd_top ./tools/perf/builtin-top.c:1774 > #6 0x55d8b87176b7 in run_builtin ./tools/perf/perf.c:313 > #7 0x55d8b8717c10 in handle_internal_command ./tools/perf/perf.c:365 > #8 0x55d8b8717fcd in run_argv ./tools/perf/perf.c:409 > #9 0x55d8b87187bc in main ./tools/perf/perf.c:539 > > SUMMARY: AddressSanitizer: heap-use-after-free > ./tools/include/linux/compiler.h:132 in __read_once_size > Shadow bytes around the buggy address: > 0x0c0680001060: fa fa fa fa fa fa fa fa fd fd fd fd fa fa fa fa > 0x0c0680001070: fa fa fa fa fa fa fa fa fa fa fd fd fd fd fa fa > 0x0c0680001080: fa fa fa fa fa fa fa fa fa fa fa fa fd fd fd fd > 0x0c0680001090: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > 0x0c06800010a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa > =>0x0c06800010b0: fa fa fa fa fa fa fd fd fd[fd]fa fa fa fa fa fa > 0x0c06800010c0: fa fa fa fa fa fa fa fa fd fd fd fa fa fa fd fd > 0x0c06800010d0: fd fa fa fa fd fd fd fd fa fa fd fd fd fa fa fa > 0x0c06800010e0: fd fd fd fd fa fa fd fd fd fd fa fa fd fd fd fa > 0x0c06800010f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fd fd > 0x0c0680001100: fd fd fa fa fa fa fa fa fa fa fa fa fa fa fa fa > Shadow byte legend (one shadow byte represents 8 application bytes): > Addressable: 00 > Partially addressable: 01 02 03 04 05 06 07 > Heap left redzone: fa > Freed heap region: fd > Stack left redzone: f1 > Stack mid redzone: f2 > Stack right redzone: f3 > Stack after return: f5 > Stack use after scope: f8 > Global redzone: f9 > Global init order: f6 > Poisoned by user: f7 > Container overflow: fc > Array cookie: ac > Intra object redzone: bb > ASan internal: fe > Left alloca redzone: ca > Right alloca redzone: cb > Shadow gap: cc > ==235440==ABORTING > > My hope was to land this so that 'perf test' wouldn't have new > failures caused by leak sanitizer. So one option could be to guard the > change with an address sanitizer #ifdef. The larger fix is to rework > the reference counting logic, but I'd really hope we could switch that > work to being in a language like Rust to get us out of the current > memory leak vs crash wac-a-mole. > > +Riccardo as he did some great and related fixes over the summer. > > Thanks, > Ian > > > > > - Arnaldo > > > > > thanks, > > > jirka > > > > > > > --- > > > > tools/perf/util/map.c | 1 + > > > > 1 file changed, 1 insertion(+) > > > > > > > > diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c > > > > index 8af693d9678c..ceed8f407bc0 100644 > > > > --- a/tools/perf/util/map.c > > > > +++ b/tools/perf/util/map.c > > > > @@ -192,6 +192,7 @@ struct map *map__new(struct machine *machine, u64 start, u64 len, > > > > if (!(prot & PROT_EXEC)) > > > > dso__set_loaded(dso); > > > > } > > > > + nsinfo__put(dso->nsinfo); > > > > dso->nsinfo = nsi; > > > > > > > > if (build_id__is_defined(bid)) > > > > -- > > > > 2.34.0.rc2.393.gf8c9666880-goog > > > > > > > > -- > > > > - Arnaldo
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